Rheostat.



W. T. LYON.

RHEOSTAT.

APPLICATION FILED SEPT. 24. 1914.

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W. T. LYON.

RHEOSTAT.

APPLICATION man SEPT. 24, 1914.

Patented Nov. 14, 1916.

2 SHEETS-SHEET 2.

UNITED sTATEs PATENT oEEIoE.

WILLIAM T. LYON, OF PORTLAND, OREGON, ASSIG'NOR TO THE INTERNATIONALDENTAL APPLIANGE CO.,

OF PORTLAND, OREGON.

RHEOSTAT.

Specication of Letters Patent.

Patented Nov. 14, 1916.

To all whom t may concern Be it known that I, WILLIAM T. LYON, residingat Portland, in the county of Multnomah and State of Oregon, haveinvented certain new and useful Improvements in Rheostats, of which thefollowing is a'speciication.

My invention relates to certain new and useful improvements in currentcontrolling devices, commonly known as rheostats, and the inventionprimarily has for its object to provide a simple, compact, inexpensiveand well constructed device of this character.

which is especially adapted for use in controlling electric motorsemployed for driving dental instruments and the like, and in its genericnature the invention comprises a rheostat having an operating leverwhich continuously tends to assume a neutral position under springinfluence and which when moved in one direction will control the motorto effect a turning of the drive shaft of the same in a given direction,and when the lever is moved in the opposite direction the motor will bereversed, and accordingly controlled as to its speed dependent upon thedegree to which the lever is moved from its neutral position.

More speciiically the invention comprises s a supporting base having aseries of resistance contacts that are adapted to be successivelyengaged by the movement oi a lever from a mid-position to one side orthe other of such mid-position, the base also carrying pole changingcontacts which are adapted to be engaged by an auxiliary memmer that isseparately pivoted on the base and has a pin and slot connection withthe lever whereby as the lever is moved out of its neutral position, thepole changing contact member will be accordingly moved Ito eiiect theproper connections with the motor to cause it to turn in a definitedirection, dependent upon whether or not the lever is moved to one sideor the other.

The invention also includes certain improvements in the arrangement ofthe driving motor and the operative connections between the motor andthe dental instrument.

In its more subordinate nature, the invention also includes those noveldetails of construction, combination and arrangement of parts, all ofwhich will be fully described, then be specifically pointed out in theappended claims and illustratedin the accom'- panying drawings, in whichFigure l is a side elevation illustrating` my invention in use. Fig. 2is a diagrammatic view showing the circuit connections for thecontroller. Fig. 3 is a horizontal section on the line 3-3 on Fig. 4.Fig. 4 is a vertical section on the line 4 4 of Fig. 3, the parts beingin the neutral or non-operative position. Fig. 5 is a. View similar toFig. 3, showing the position of theparts when the lever is moved to itslimit to one side of its neutral position to cut out all resistance, andoperate the motor at full speed in a 4given direction. Fig. 6 is anenlarged detail cross section of a contact member such as may be carriedby the operating lever to vbridge the continuous contact with theresistance contact points. Fig. 7 is a detail top plan view showing theclamping nut. Fig. 8 is a detail enlarged perspective view of the polechanging segment. Fig. 9 is an enlarged Vdetail perspective view of themotor showing the swivel connection with the dental instrumentsupporting arm. Fig. 10 is a detail cross section of the same.

ln the drawings in which like letters and numerals of reference indicatelike parts in all of the Iigures, 1 represents the motor support whichis secured to the dental chair by a suitable clamp or bracket 2, and 3designates the motor which is preferably of the inclosed type and ismounted on the top of the support 1.

rlhe motor 3 has its shaft 4 provided with a driving pulley 5 and themotor casing 1s providedwith a neck 7 having an annular groove 8 to-receive the set, screw 9 which holds the swivel collar 6 in place, theswivel collar 6 carrying the sweep arm 10 that 1s provided with a swiveljoint 11 and wlth an extension portion 12 of the sweep arm, the swiveljoint 11 including idler pulleys over which y the endless driving beltI14 passes, the belt 14: also passing over Idler pulleys 13 on the swiveljoint between the arm 12 and the bracket 15 which carries the hand piece16. u

17 is a support on which the hand piece may be placed when not in useand 18 is an idler pulley which rides on the surface7 19 of the motorhousing to assist in supporting the parts. y

20 designates the controller or rheostat which forms the essential partof the present invention. The controller comprises a base plate 21 and acover 22. Deposited within the cover 22 is a block of insulation 24 inwhich resistance coils 36 are embedded. On a pivot 23 vsecurely fastenedin the block 24 by any approved means is a lever 30, a pair of washers28-29, and a clamp nut 25, the lever 30 being interposed between thewashers'28-29 for a purpose presently understood. The clamp nut 25 has amilled face 27 whereby when the foot of the operator is placed on thenut, the nut may be turned by foot so as to clamp the lever in anyposition in which it may be placed, thus serving as a""releasable meansfor holding the lever in any of its positions. When the` member 25 isturned to secure it onto the pin 23 by the' operator putting his foot onthe -member 25 and turning it, the ,lever is clamped tight, but when themember 25 is turned in the reverse direction to unscrew it from the pin23, the lever is released. The lever 30 projects through the opening inthe cover 22 and carries the Yinsulated handle 31 to which it is securedby a bolt 32 or secured in any other suitable way.

33 designates suitable springs for keeping the lever 30 balanced in amid or neutral position. Any approved construction of spring device maybe employed for this purpose.

34 is a contact strip to which one of the leading-in wires 49 iselectrically connected and 35 designates the series of resistancecontact points which lare electrically con- .secured to the base 24, isa segment 39 which has a "pair'of contact plates 40-41 respectivelyY tobridge the contacts 43 .to 46 inclusive.V The segment 39 has a slot 47to receive the pin 48 that is carried by the lever 30 whereby to make apin and slot connection between the lever and the segment.

49 designates the leading-in wires from the current source, one of whichis connected to the plate 34, and the other is connected to the polechanging contact 44.

50 designates the armature wires to the motor 3, one of which isconnected to the contact 43 while the other is connected to the contact45, vthe contacts 42-46 being electrically connected together and tothe.

contacts 35, as shown in Figs. 2 and 3.

When the parts are in'the ,position shown in Fig. 3, no current will iowto the motor as the'contact 51 is a dead contact and there isno circuitconnection between the contacts 42-46, 43 or 45.

The operator upon engaging the handle contact 37 to the lowermostcontact 35 in Fig. 5, and from thence to contact 46, across plate 41 tocontact 45 and from thence throughthe motor armature, returning viacontact 43, across plate 40 to contact 44 and from thence back to thesource of current supply. If the position of the lever be reversed inFig. 5, the current flow through the motor I'Will also be reversed withthe result that the motor will turn in the opposite direction. The speedunder which the motor operates is determined by theV amount ofresistance cut in, as will be clearly understood by those skilled in theart.

While I have Vdesignated the resistance coils 36 as located in the base24, it is obvious they may be elsewhere located, if desired', withoutdeparting from the spirit of the invention or the scope of the appendedclaims. l

The rheostat may be readily 'disconnected from the motor, since aconnection is provided at the ends of the wires 50, as indicated in Fig.1, a switch for cutting the current to the motor 0H and on is alsoprovided.

The provision of a tightener 14t for the endless belt 14 and the placingof the motor 3 on a wall bracket instead of on the standard 1, are merefeatures of convenience and may be provided for at will.

From the foregoing description, taken in connection with vtheaccompanying drawings, it is thought the complete construction,operation and advantages of my invention will be readily understood bythose skilled in the art to which it relates.

What I claim is:

1. In a motor controller, a base, a set of resistance contacts, a set ofpole changing contacts, a lever coperating with said resistancecontacts, a pivoted segment coperative with said pole changing contacts,a pin and slot connection between said pivoted segment and said lever tocoperatively connect the same, means for applying balanced pressures tosaid lever to continuously tend to hold it ina neutral position, and afoot operable `clamping device for securing said lever in any of itspositions.

2.. In a motor controller, a base, a set of resistance contacts, a setof pole changing contacts, a lever coperating with said resistancecontacts, a pivoted segment cooperating with said pole changingcontacts, coperative connections between said lever and said segmentwhereby the movement of the lever from a neutral position will effect asimilar movement of said segment, a pivot pin upon which said lever isfulcrumed, and a device on said pin for clamping said lever in any ofits positions.

3. In a motor controller, a base, a set of resistance contacts, a set ofpole changing contacts, a lever coperative with said resistancecontacts, a pivoted member cooperative with said pole changing contacts,a pin and slot connection between said pivoted member and said lever tocoperatively connect the same, a pivot pin upon which said lever isfulcrumed, and a device on said pin for clamping said lever in any ofits positions.

4. In a motor controller, a base, a set of resistance contacts, a set ofpole changing contacts, a lever coperating with said resistancecontacts, a pivoted segment cooperating with said pole changingcontacts,

coperative connections between said lever and said segment whereby themovement of the lever from a neutral point will eiiect a similarmovement of said segment, means continuously acting to hold said leverin a neutral position, a pivot pin upon which said lever is fulcrumed,and a device on said pin for clamping said lever in any of itspositions.

5. In a motor controller, a base, a set of resistance contacts, a set ofpole changing contacts, a lever cooperating with said resistancecontacts, a pivoted member cooperative with said pole changing contacts,a pin and slot connection between said pivoted member and said lever tocooperatively connect the same, means continuously acting to hold saidlever in a neutral position a pivot pin upon which said lever isfulcrumed, and a device on said pin for clampmg said lever in any of itspositions.

VILLIAM T. LYON.

lVitnesses:

A. T. LEWIS, ARTHUR H. LEWIS.

